On 3/24/2020 1:02 AM, Thomas Gleixner wrote:
Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes:Current initialization flow of split lock detection has following issues: 1. It assumes the initial value of MSR_TEST_CTRL.SPLIT_LOCK_DETECT to be zero. However, it's possible that BIOS/firmware has set it.Ok.2. X86_FEATURE_SPLIT_LOCK_DETECT flag is unconditionally set even if there is a virtualization flaw that FMS indicates the existence while it's actually not supported. 3. Because of #2, KVM cannot rely on X86_FEATURE_SPLIT_LOCK_DETECT flag to check verify if feature does exist, so cannot expose it to guest.Sorry this does not make anny sense. KVM is the hypervisor, so it better can rely on the detect flag. Unless you talk about nested virt and a broken L1 hypervisor.
Yeah. It is for the nested virt on a broken L1 hypervisor.
